Make Your Career Soar
Fifty-three years ago this month, the USAF/RCA Project SCORE spacecraft became the world’s first communications satellite. Within 24 hours of being orbited by an Atlas B intercontinental ballistic missile (ICBM), the SCORE (Signal Communications Orbit Relay Equipment) payload broadcast a Christmas message to the world recorded by U. S. President Dwight D. Eisenhower. The president’s message was the first time a human voice was heard from space.
Sixty-four years ago this month, the USAF/Boeing XB-47 Stratojet took to the air for the first time. The legendary Stratojet would go on to become the first all-turbojet strategic bomber to enter operational service with the United States Air Force.
Fifty-seven years ago this month, the USAF/Boeing B-29 Superfortress strategic bomber was officially retired from the active inventory of the United States Air Force. The famed World War II-era aircraft had a service life of less than a dozen years.
Fifty-six years ago this month, the USAF/Bell X-2 Starbuster experimental flight research aircraft made its initial powered flight from Edwards Air Force Base, California. Legendary test pilot USAF Lt. Col. Frank K. “Pete” Everest was at the controls of the rocket-powered, swept-wing X-aircraft.
Fifty-four years ago this month, the first ablative nose cone to survive entry into the Earth’s atmosphere was formally presented to the American public. President Dwight D. Eisenhower displayed the recovered nose cone during a national television broadcast from the Oval Office.
An object making a hypersonic entry into the the Earth’s atmosphere from space possesses a great deal of kinetic energy. This energy of motion is transformed to thermal energy as aerodynamic drag slows the vehicle during atmospheric flight. A portion of the entry thermal energy is absorbed by the vehicle structure in a process referred to as aerodynamic heating. This heat transfer process causes the temperature of the external surface of the vehicle to significantly increase.
From a vehicle survivability standpoint, three parameters are key; (1) maximum heat transfer rate, (2) maximum surface temperature and (3) total thermal energy absorbed by the vehicle during entry. The concern is that there is enough kinetic energy in the entry flight domain to vaporize any known material if that energy is completely absorbed by the vehicle.
One has only to look into the heavens at night to become convinced of the ferocity of the entry environment. The streaks of white, yellow, green, blue, or red light that dramatically flash into and out of existence are associated with the vaporization of meteors transiting the atmosphere. Few meteors have enough original mass to allow a minor portion thereof to reach the ground. Those that do are referred to as meteorites.
The problem of surviving atmospheric entry was a major research topic in the 1950’s. Attention focused on protecting the nuclear warhead carried by the reentry vehicle of an Intercontinental Ballistic Missile (ICBM). A pair of research scientists at the NACA Ames Research Center in California, H. Julian Allen and Alfred J. Eggers, are credited with solving the problem. The key was to hemispherically-blunt or round the nose of a reentry vehicle.
A blunted forebody disposes a detached, hyperbolic-shaped shock wave which slows the post-shock flow to subsonic speeds in the stagnation region. A byproduct of this flow deceleration is a significant increase in post-shock static pressure and temperature. While this dramatically increases vehicle wave drag, most of the high temperature air passes around the vehicle and thus never physically comes in contact with it. The result is that only a small fraction of the overall thermal energy of the freestream flow is convected to the vehicle surface.
In contrast to the above, a sharp-nosed vehicle nose disposes an attached, highly-swept shock wave. This flow topology results in a large fraction of the overall thermal energy being convected to the vehicle surface. The is because the degree of post-shock flow slowing in such a situation is small. Indeed, the post-shock flow has a high supersonic Mach number. Now, due to the “no-slip” condition caused by fluid viscosity, the flow velocity at the vehicle surface is zero. Thus, the bulk of the flow deceleration has to occur within the boundary layer. The huge shearing stresses and temperature gradients that result generate extreme heat flux rates at the vehicle surface.
On Thursday, 08 August 1957, a Jupiter-C launch vehicle carrying a one-third scale version of a Jupiter IRBM nose was launched from LC-6 at Cape Canaveral, Florida. The nose cone traveled 1,168 nautical miles, reaching nearly 9,000 mph and an altitude of 260 nautical miles in the process. During reentry an ablative heat shield was used to protect the nose cone from the aerodynamic heating environment. The vehicle parachuted into the Atlantic Ocean and was recovered by Navy swimmers within three hours of launch.
On Thursday, 07 November 1957, President Dwight D. Eisenhower displayed the recovered Jupiter IRBM scaled nose cone in a nationally televised broadcast from the Oval Office. The excellent condition of the recovered vehicle was a stark testament to the effectiveness of a blunted, ablative nose cone to weather the rigors of reentry heating. This historic breakthrough would forever change the science of atmospheric entry. Indeed, it would ultimately make possible successful entry of Apollo astronauts returning from the Moon at 25,000 mph.
Today, one can view the recovered Jupiter IRBM subscale nose cone at the Smithsonian’s National Air and Space Museum in Washington, DC. Specifically, it is on public display in the Space Race Exhibition at the National Mall Building.
Forty-four years ago this month, the No. 3 USAF/North American X-15 research aircraft broke-up during a steep dive from an apogee of 266,000 feet. The pilot, USAF Major Michael J. Adams, died when his aircraft was torn apart by aerodynamic forces as it passed through 65,000 feet at more than 2,500 mph.
The hypersonic X-15 was arguably the most productive X-Plane of all time. Between 1959 and 1968, a trio of X-15 aircraft were flown by a dozen pilots for a total of 199 official flight research missions. Along the way, the fabled X-15 established manned aircraft records for speed (4,534 mph; Mach 6.72) and altitude (354,200 feet).
The X-15 was a rocket, aircraft and spacecraft all rolled into one. Burning anhydrous ammonia and liquid oxygen, its XLR-99 rocket engine generated 57,000 lbs of sea level thrust. Reaction controls were required for flight in vacuum. Each flight also required careful management of aircraft energy state to ensure a successful, one attempt only, unpowered landing.
On Wednesday, 15 November 1967, the No. 3 X-15 (S/N 56-6672) made the 191st flight of the X-15 Program. In the cockpit was USAF Major Michael J. Adams making his 7th flight in the X-15. He had been flying the aircraft since October of 1966. Like all X-15 pilots, he was a skilled, accomplished test pilot used to dealing with the demands and high risk of flight research work.
X-15 Ship No. 3 was launched from its B-52B (S/N 52-0008) mothership over Nevada’s Delamar Dry Lake at 18:30 UTC. As the X-15 fell away from the launch aircraft at Mach 0.82 and 45,000 feet, Adams fired the XLR-99 and started uphill along a trajectory that was supposed to top-out around 250,000 feet. If all went well, Adams would land on Rogers Dry Lake at Edwards Air Force Base in California roughly 10 minutes later.
Around 85,000 on the way upstairs, Adams became distracted when an electrical disturbance from an onboard flight experiment adversely affected the X-15’s flight control system, flight computer and inertial reference system. As a result, data on several key cockpit displays became corrupted. Though with some difficulty, Adams pressed-on with the flight which peaked-out around 266,000 feet approximately three (3) minutes from launch.
As a result of degraded flight systems and perhaps disoriented by vertigo, Mike Adams soon discovered that his aircraft was veering from the intended heading. He indicated to the control room at Edwards that his steed was not controlling correctly. Passing through 230,000 feet, Adams cryptically radioed that he was in a Mach 5 spin. Mission control was stunned. There was nothing in the X-15 flight manual that even addressed such a possibility.
Incredibly, Mike Adams somehow managed to recover from his hypersonic spin as the X-15 passed through 118,000 feet. However, the aircraft was inverted and in a 45-degree dive at Mach 4.7. Still, Adams may very well have recovered from this precarious flight state but for the appearance of another flight system problem just as he recovered the X-15 from its horrific spin.
X-15 Ship No. 3 was configured with a Minneapolis-Honeywell adaptive flight control system (AFCS). Known as the MH-96, the AFCS was supposed to help the pilot control the X-15 during high performance flight. Unfortunately, the unit entered a limit-cycle oscillation just after spin recovery and failed to change gains as the dynamic pressure rapidly increased during Ship No. 3’s final descent. This anomaly saturated the X-15 flight control system and effectively overrode manual inputs from the pilot.
The limit-cycle oscillation drove the X-15’s pitch rate to intolerably-high values in the face of rapidly increasing dynamic pressure. Passing through 65,000 feet at better than 2,500 mph (Mach 3.9), Ship No. 3 came apart northeast of Johannesburg, California. The main wreckage impacted just northwest of Cuddeback Dry Lake. Mike Adams had made his final flight.
For his flight to 266,000 feet, USAF Major Michael J. Adams was posthumously awarded Astronaut Wings by the United States Air Force. His name was included on the roll of the Astronaut Memorial at Kennedy Space Center (KSC) in 1991. Finally, on Saturday, 08 May 2004, a small memorial was erected to the memory of Major Adams near his X-15 crash site situated roughly 39 miles northeast of Edwards Air Force Base.
Fifty-four years ago today, the USAF/Northrop SNARK intercontinental cruise missile successfully flew its maximum range mission of 5,000 statute miles for the first time. SNARK would go on to become the only strategic cruise missile ever operationally deployed by the United States.
The SM-62A SNARK was designed to deliver nuclear ordnance at strategic ranges. The vehicle was conceived as an autonomous, winged, turbojet-powered aircraft with a high subsonic cruise capability. Ground launch was provided by a pair of disposable, high-thrust rocket boosters. The SNARK’s origins date back to the middle 1940’s.
The missile’s name, SNARK, is not an acronym. Rather, SNARK has reference to the mythical creature highlighted in Lewis Carroll’s poem, “The Hunting of the Snark”. Jack Northrop, president of Northrop Aircraft Company, developer of the SNARK, is credited with selection of the missile’s name.
SNARK engineering development and flight testing took place between 1946 and 1960. This protracted gestation period was partially due to mission requirements drift on the part of the Air Force. However, challenging technical problems, a flat funding profile and mission relevancy issues also served to draw-out the development effort.
The original SNARK prototype was designated as the N-25 by Northrop. The missile was designed to fly 1,550 statute miles and cruise at Mach 0.85. N-25 flight testing occurred between December of 1950 and March of 1952. While the results were not particularly encouraging, USAF still wanted a strategic cruise missile. This led to the development of a larger, more capable airframe designated as the N-69.
The N-69 SNARK configuration measured 67.2 feet in length and featured a wing span of 42.25 feet. Launch weight was roughly 49,000 lbs. Power was provided by a single Pratt and Whitney J-57 turbojet that generated a sea level thrust of 10,500 lbs. The missile carried a single W39 nuclear warhead with a yield of 3.8 megatons. The SNARK was ground-launched using a pair of Aerojet General solid propellant rocket boosters that produced a combined thrust of 260,000 lbs. The complete launch stack weighed 60,000 lbs.
The design operational range for the N-69 airframe was 5,500 nm. The type had a top cruise speed and ceiling of 650 mph and 50,000 feet, respectively. Maximum mission time was on the order of 11 hours. Northrop was constrained to use a celestial navigation system to get the SNARK to its distant target. The company optimistically advertised a CEP of 8,000 feet.
On Thursday, 31 October 1957, a SNARK N-69E airframe (S/N N-3324) successfully flew a strategic range flight for the first time. Launch occurred from either LC-1 or LC-2 (the historical record is unclear here) at Cape Canaveral, Florida. The missile flew 5,000 statute miles to its target near Ascension Island in the South Atlantic Ocean.
While the range achieved on the SNARK’s Halloween 1957 flight test was impressive, guidance system accuracy was quite poor. Indeed, guidance system performance deficiencies plagued the SNARK Program throughout its life. Witness the fact that through May of 1959, the best the SNARK guidance system could do on long range flights was impact within 4.3 nm of the target. Moreover, the first guidance flight to be successfully completed did not occur until February of 1960.
The latter 1950’s saw rapid development of successful Intercontinetal Ballistic Missile (ICBM) systems within the United States and the Soviet Union. These suborbital warhead delivery systems outperformed the SNARK by every measure. In spite of its obvious obsolescence, low reliability and marginal accuracy, USAF opted to field the weapon anyway.
The first and only SNARK missile wing, consisting of 30 airframes, was operationally-deployed at Presque Isle AFB, Maine in February of 1961. However, the type’s deployment period would be brief. Newly-inaugurated President John F. Kennedy cancelled the SNARK Missile Program soon after taking office. As a result, the SNARK missile wing at Presque Isle AFB was deactivated in June of 1961.
America’s aerospace history is filled with unique aerospace systems that saw limited or no operational service. Notable examples include the Navaho, B-70, F-107, X-20 and the X-33. While these vehicles never filled the measure of their creation, the technology and capability accrued during their development greatly benefitted succeeding generations of aerospace craft. Such is the case for SNARK. Indeed, historically importnant operational missile systems such as Jupiter, Atlas, Minuteman and Titan were direct heirs of technology, capability and technical lessons-learned derived from the SNARK experience.
Fifty-nine years ago this month, the USN/Douglas XA3D-1 Skywarrior prototype strategic bomber made its initial test flight at Edwards Air Force Base, California. Legendary Douglas test pilot George R. Jansen was at the controls of the swept-wing, turbojet-powered, carrier-based aircraft.
The USN/Douglas A3D Skywarrior was the product of late 1940’s Navy studies calling for a carrier-based, long range bomber capable of delivering a 10,000 lb bomb load. Douglas Aircraft Company was awarded a contract to manufacture and test a pair of XA3D-1 airframes (BuAer No. 125412 and No. 125413) in 1949. Westinghouse was selected as the powerplant provider.
The XA3D-1 had a design weight of roughly 68,000 lbs, which would allow the aircraft to operate from existing Navy aircraft carriers. Power was provided by a pair of Westinghouse J40 turbojets. Each of these powerplants generated 7,500 lbs of military thrust and 10,500 lbs of afterburner at sea level. Unfortunately, the XA3D-1 was underpowered with these powerplants. In any event, the J40 engine experienced significant development problems and never did see production.
The No. 1 XA-3D-1 (BuAer 125412) made its maiden flight on Tuesday, 28 October 1952 with Douglas test pilot George R. Jansen doing the piloting honors. Although a Navy program, the flight was conducted at Edwards Air Force Base in California. The safety provided by the presence of the world’s longest (11.5 miles) natural runway, Rogers Dry Lake, was one reason for doing so. The XA3D-1 initial test hop was unremarkable.
The results of early Skywarrior testing significantly aided the evolutionary development and improvement of the aircraft. The A3D-1 was the first Skywarrior variant to see limited production. This was ultimately followed by the A3D-2; considered by many to be the definitive Skywarrior. Large for a carried-based aircraft, the Skywarrior was nick-named “The Whale”.
The A3D-2 measured 76.3 feet in length and had a wing span of 72.5 feet. Wing leading edge sweep and planform were 36-deg and 812 square feet, respectively. The aircraft had a GTOW of 82,000 lbs versus a empty weight of 39,400 lbs. Power was provided by twin Pratt and Whitney J57-P-10 turbojets. Each powerplant generated 10,500 lbs of military thrust at sea level. Each engine could produce an additional 2,400 lbs of thrust using water injection.
The A3D-2 could carry a maximum conventional or nuclear bomb load of 12,800 lbs. Maximum unrefueled range was 1,826 nm. With a service ceiling of 41,000 feet, the aircraft typically cruised at 452 knots. Maximum airspeed was 530 knots. The A3D-2 flight crew consisted of a pilot, navigator and bombardier. Interestingly, the crew was not provided with ejection seats as a cost-saving measure. This led Skywarrior crews to asert that “A3D” was actually an acronym that meant “All 3 Dead”.
While the Skywarrior was designed as a strategic bomber, the aircraft was used in other roles over the course of its long operational life. Indeed, the Skywarrior was modified to serve in the electronic warfare role, as a photo-recon platform and as an aerial tanker. Historical records indicate that 282 Skywarriors were produced between 1956 and 1961.
The Skywarrior and its crews served faithfully throughout the Cold War period including Vietnam. Significantly, the Skywarrior holds the distinction of being the largest and heaviest aircraft ever to see operational service aboard an aircraft carrier. The last operational Skywarriors were taken out of the active inventory in September of 1991.
As a further tribute to the Skywarrior, the Air Force liked the aircraft so much that it contracted with the Douglas Aircraft Company to design, test and produce a very similar aircraft; the B-66 Destroyer. First flight occurred in June of 1954. Operationally, the B-66 was used primarily in the electronic warfare and recon roles. A total of 294 airframes were ultimately produced for the junior service. Happily, ejection seats were standard equipment.
Thirty-seven years ago this month, the first USAF/Rockwell B-1A multi-role strategic bomber was rolled-out at the contractor’s USAF Plant 42 facility in Palmdale, California. The swing-wing, supersonic aircraft was intended to replace the venerable USAF/Boeing B-52 Stratofortress.
The USAF/Rockwell B-1A Lancer was the product of 1960’s-era Air Force studies calling for a supersonic-capable, low-level penetration bomber. North American Rockwell was awarded a contract to manufacture and test four (4) prototype airframes (S/N’s 74-0158, 74-0159, 74-0160 and 76-0174) in 1970. General Electric was selected as the powerplant provider.
The B-1A was designed for both Mach 2.3 flight at 50,000 feet and Mach 0.85 flight at sea level. The aircraft was able to satisfy these requirements by virtue of several design features. Formost among these was the aircraft’s ability to adjust its wing sweep in flight. Coupled with its sleek, aerodynamically-efficient fuselage, this gave the aircraft very low wave drag. Another key element were the type’s quartet of General Electric F-101 turbofan engines which generated a total of 120,000 lbs of afterburner thrust at sea level. Thrust performance was optimized through the use of variable-geometry air intakes.
The B-1A measured 150.2 feet in length and featured a wing span that could be varied in flight from 136.7 feet (15-deg sweep) to 78.2 feet (67.5-deg sweep). Gross take-off and empty weights were 395,000 lbs and 115,000 lbs, respectively. Unrefueld range was 5,300 nm. The aircraft was designed to carry 75,000 lbs of nuclear and/or conventional ordnance internally and up to 40,000 lbs externally. Operationally, the B-1A’s four-man crew would consist of aircraft commander, pilot, offensive systems officer and defensive systems officer.
The No. 1 B-1A (S/N 74-0158) was rolled out for the public on Saturday, 26 October 1974. About 10,000 people attended this event which took place at Rockwell’s facility on USAF Plant 42 property in Palmdale, California. The big, white, sleek aircraft was visually stunning and bore a majestic presence. The media covered the event in some detail.
The No. 1 B-1A took-off for the first time from USAF Plant 42 on Monday, 23 December 1974. The flight test aircrew included Charles Bock, Jr. (aircraft commander), Col. Emil (Ted) Sturmthal (pilot) and Richard Abrams (flight test engineer). The aircraft’s landing gear was not retracted and wing sweep was not varied during this initial flight test. These systems were operated on the type’s second flight test which occurred on Thursday, 23 January 1975.
Each of the B-1A prototypes served a distinct role in the aircraft’s flight test program. The No. 1 aircraft (74-0158) was the flying qualities evaluation testbed. It flew 79 times (405.3 hours) and was the first B-1A to hit Mach 1.5 (Oct 1975) as well as Mach 2 (Apr 1976). Aircraft No. 2 (S/N 74-0159) evaluated structural loading parameters, flew 60 times (282.5 hours), and achieved the highest Mach number of any B-1A aircraft (Mach 2.22 on Oct 1978). Aircraft No. 3 (S/N 74-0160) amassed 138 flights (829.4 hours) as an offensive and defensive systems testbed. Aircraft No. 4 (76-0174) had a similar role in that it tested essentially operational versions of the offensive and defensive systems. It flew 70 times (378 hours).
The B-1A program was cancelled by the Carter Administration in June of 1977. While it never attained operational status, the aircraft broke new ground in mutiple areas including aircraft design, aerodynamics, flight performance, and electronic warfare. Indeed, the multiple technological capabilities that it pioneered were ultimately exploited in the type’s direct heir; today’s USAF B-1B Lancer.
Fifty-six years ago this month, the USAF/Republic YF-105A Thunderchief took to the air for the first time from Edwards Air Force Base. With Republic test pilot Russell M. Roth at the controls, the fabled Thud exceeded the speed of sound during its maiden flight.
The USAF/Republic F-105 Thunderchief was a member of the fabled Century Series of jet-powered production aircraft. It was designed specifically as a fighter-bomber capable of delivering nuclear ordnance. Famed Republic aircraft designer Alexander Kartveli is credited with creation of the F-105 airframe.
The Thunderchief was a big airplane. The original version (YF-105A) measured 61.5 feet in length and featured a wing span of 35 feet. Gross take-off and empty weights were 40,561 lbs and 28,966 lbs, respectively. Power was provided by a single Pratt and Whitney J57-P-25 turbojet which produced 15,000 lbs in afterburner thrust at sea level.
The YF-105A was designed to have a maximum speed of 778 mph at sea level and a maximum speed at 36,000 feet of 857 mph. The aircraft had a combat ceiling of 49,950 feet and could carry an ordnance load of about 8,000 lbs. With an internal fuel load of 850 gallons, the aircraft could fly 878 nm. Range was increased to 2,364 nm with the addition of 1,870 gallons carried externally.
The first YF-105A Thunderchief (S/N 54-0098) made its maiden flight on Saturday, 22 October 1955. This initial test hop was conducted at Edwards Air Force Base, California, with Republic test pilot Russel M. Roth doing the piloting honors. Despite a high level of transonic drag resulting from the lack of fuselage area-ruling, the aircraft hit Mach 1.2 on its first time in the air.
The Thunderchief entered the USAF inventory in May of 1958 as the F-105B. A number of variants followed in the years that followed. The F-105D was the definitive single-seater version. The F-105F served as a combat-capable trainer. The F-105G was also a two-seater and flew the Wild Weasel mission.
Performance of the later versions of the Thunderchief significantly exceeded that of the YF-105A. For example, the F-105D Thunderchief was powered by a Pratt and Whitney J75-P-19W turbojet that produced 24,500 lbs of thrust in afterburner. The engine was fed by side-mounted, variable-geometry, forward-swept air intakes that were more efficient than the original design. Further, the fuselage employed area-ruling to reduce transonic wave drag. Taken together, these changes gave the Thunderchief a Mach 2+ capability.
The F-105D had a gross take-off weight of 52,546 lbs carrying a 14,000 lb conventional ordnance load-out. Empty weight was 27,500 lbs. The aircraft’s small wing area (385 square feet) resulted in a very high wing loading. While this permitted very stable flight during the high-speed, low-altitude run-in to the target, the Thunderchief was no match for the agile MIG-17 flown by the North Viet Nam Air Force. Notwithstanding, the Thunderchief had 27.5 air victories against the North Vietnamese compared to 17 losses to the enemy.
Republic Aircraft manufactured a total of 833 copies of the Thunderchief by the time production ended in 1964. Viet Nam was the Thunderchief’s war. Over 20,000 sorties were flown by Thunderchief aircrews. Many of these missions were flown into the Pack VI region of the air war over North Viet Nam. A total of 382 Thunderchief aircraft were lost during the air war. This inordinately-high loss rate was largely due to the shackling and politically-motivated rules of engagement enforced by the Johnson Administration.
The F-105 no longer graces the skies. However, one can see the aircraft on display at a number of air museums throughout the country. The National Museum of the United States Air Force at Wright-Patterson Air Force Base in Dayton, OH is one such example.
In its time, the Thunderchief was a mighty performer and particularly loved by its pilots. Many books have been written by those who flew “The Thud” into hostile skies. These personal accounts are quite inspiring and often poignant. To get a sense of what it was like to fly and fight in the Thunderchief, Jack Broughton’s “Thud Ridge” is an unforgettable read.
